With the advent of point of care testing in medical settings, it has become increasingly important to have diagnostic products which are simple, rapid and convenient for the user to perform. Thus, health care workers in emergency settings need results rapidly, and have minimal time to perform a diagnostic test. The rapid availability of a diagnostic result allows a physician to treat a patient as soon as possible.
Point of care diagnostic tests often are performed on biological samples, such as whole blood or urine. However, cells and particulate matter in biological samples can interfere with fluid flow in a test device, and thus impair the measurement of analytes in the biological fluid.
For example, in blood samples, red blood cells can interfere with spectroscopic measurements; such interference is further affected by hematocrit, since as the hematocrit varies, the volume of plasma in a given volume of blood varies. To overcome these problems, red blood cells are often separated from plasma to allow for a more defined and uniform sample.
For certain analytes to be assayed in a blood sample, however, analysis of plasma or serum does not accurately reflect the amount of the analyte in the biological sample. For example, therapeutic agents such as cyclosporin, or metabolic molecules such as hemoglobin and hemoglobin A1c (HbA1c), need to be evaluated in both extracellular and intracellular spaces to obtain an effective assay result. To evaluate analyte levels both intracellularly and extracellularly, cellular components are lysed, and thereafter a liquid sample containing mixed extracellular and intracellular fluids is assayed.
Assay results for analytes such as hemoglobin, hemoglobin A1c and cyclosporin are often needed on a point of care basis. Accordingly, there is a need for assay devices that permit rapid assay results of an analyte present in extracellular and intracellular compartments of a biological sample.
Thus, there is a need for an efficient, compact, cost-effective device structure to facilitate lysis of cells in biological samples. There is also a need for devices that achieve cellular lysis and thereafter provide an assay result on both extracellular and intracellular contents.